Well pressure responsive valve

ABSTRACT

A subsurface valve to control the flow of fluid in the bore of the well tubing. The valve has an operator which responds to control line pressure to cause a plug to seat in the bore tubing and prevent flow therethrough. The operator is maintained outside the bore and the plug is normally in a position offset from the bore. One form of the invention includes a movable sleeve for preventing movement of the plug toward seating position.

United States Patent [56] References Cited UNITED STATES PATENTS 1/1962Natho........................... 2,635,626 4/1953 Meynig.....

[72] Inventor Cliva A. Rowell, Jr.

Long Beach, Calif. [21] Appl. No. 830,719

166/72 137/461X l37/461X 2,935,998 5/1960 Richardson 3,269,463 8/1966Page........... 3,411,585 11/1968 Page...............

Primary Examiner-Ian A. Calvert Attorney-Lyon & Lyon ABSTRACT: Asubsurface valve to control the flow of fluid in the bore of the welltubing. The valve has an operator which responds to control linepressure to cause a plug to seat in the bore tubing and prevent flowtherethrough. The operator is maintained outside the bore and the plugis normally in a posi* tion offset from the bore. One form of theinvention includes a movable sleeve for preventing movement of the plugtoward n O .n 0 5 a a m 2 /3 4 7 m. J wm j aw y wwzww i. v r a l 52.: el l 1 1 S IFIIWi'MIl'HVV F. 1 l 4 W a nmwmnm a 4 fiwwfiz iliii. mmmfiwnl 0% mm n 5L m u m mum W4 mm WNW NM "7 W m a m m g m m m H m m Mn g m mm .m m m m w m m m m m 6 m m r s m m m m m m r M m L o C w m 1 S M .N 2U I F n n m U r5 5 PATENTEU m 9I97l sum 1 or 2 [NVENTOR cum/4. eawag J6WELL PRESSURE RESPGNSIVE VALVE This invention relates to a fluidpressure responsive valve usable in wells, and more particularly,concerns the construction and operation of a valve which closes off flowin the bore of a well tubing when the pressure in the control line isdecreased to a value below a predetermined range.

It is frequently necessary or desirable to control the upward flow ofwell fluid in the bore of the well tubing in such a manner as to passthe flow when the production line pressure remains within normal orpredetermined levels, and to block such flow upon the occurrence ofundesirably higher or lower pressure levels which could be caused bydamage or malfunction of flow head or flow line equipment. This isaccomplished by a safety pressure booster system at the surface thatmaintains a pressure in the control line to hold a valve open duringnormal operations and normal production line pressures. Several valvedevices have been used in the past, eachwith varying degrees of success.Some of the past devices used, because of space limitations, found itnecessary to house at least a portion of the valve within the bore,thereby causing an undesirable flow restriction in the bore. Inaddition, the operation and construction of several of these valvedevices is such that frequent maintenance and repair has been required.Because of the inaccessibility of these valve devices, this maintenanceand repair is very expensive and time consuming.

Therefore, it is an object of this invention to provide a subsurfacedevice operated from the well surface which will con trol the flow offluid in the bore of the well tubing above or below a predeterminedrange of pressures within the tubing, but which will not restrict fluidflow in the bore within the predetermined range of pressures. Inaccordance with this object, the valve device should allow for full boreopening when the valve is in an inoperative position. Furthermore, thedevice should be simple in operation and construction.

Another object is to provide a device of this type employing a movablesleeve for preventing movement of the plug toward closed position.

Other objects and advantages of the invention, as well as the details ofillustrative embodiments, will be more 'fully understood by thefollowing detailed description of the drawings.

Briefly, the invention includes a pressure-actuated operator which ishoused outside the bore through which the well fluid flows. Whenpressure in the well tubing reaches a predetermined level, the controlline pressure is decreased and the operator moves upward to cause a plugnormally offset from the bore to be moved onto an annular seat in thebore to prevent the flow of the well fluid. Intermediate members, alsonormally offset from the bore, transmit force from the operator to thevalve plug and maintain the plug in the seated position. In one form ofthe invention a movable sleeve blocks the plug in its offset position.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical elevation sectioned toshow the valv device in connection with a well tubing.

FIG. 2 is a sectional view taken on line 2-2 of FIG. 1.

FIG. 3 is a sectional view taken on line 33 of FIG. 1.

FIG. 4 is a longitudinal sectional view showing a modification, theopening tool for the blocking sleeve being shown in position. 7

FIG. 5 is a view similar to FIG. 4 showing the blocking sleeve in raisedposition following removal of the opening tool.

FIG. 6 is a transverse sectional view taken on line 6-6 of FIG. 4.

Referring now in detail to FIGS. 1-3 of the drawings, the valve assemblygenerally designated 10, includes a valve body 11 which is connectedinto a well tubing 12 at any desired position within the well casing.Well or production fluid passes through the well tubing bore 13.

The valve body 11 includes a main passage or bore 14 in parallelalignment with the well tubing bore 13 and a side passage or pocketlfioffset from the well tubing bore 13. A plug 16, as seen in FIG. 1, isin the form of a ball and is carried by the valve body 11 for bodilymovement between a down or open position in the side passage 15, asshown in full lines, and an up or closed position in the bore 14, shownby the broken lines 16a. An annular seat 17 is formed at the end of thewell tubing 12 below a threaded interconnection 17a between the welltubing and the upper end of the valve body 11. The annu lar seat 17 istapered to seat and annularly fit the plug 16 and includes a plastic orresilient ring 18 to seal the space between a seated plug 16 and themetallic seat 17.

An upper side opening or port 19 in the valve body 11 between the bore14 and the side pocket 15 is sized to pass the ball plug 16 during itsmovement between the lower and unseated position and the upper andseated position. A lower side opening or port 20 in the form of anelongated slot provides for communication of the well fluid between themain passage 14 and the side passage 15-and thereby prevents sandbuildup in the side pocket 15 by allowing the sand to be washed down thebore 14 by the well fluid. The lower wall of the side passage 15 istapered downwardly at 21 to further facilitate the movement of the sandthrough the port or slotted opening 20 into the main passage 14.

A downwardly and laterally inclined ramp 22 in the bore and an upwardlytapered surface 23 at the upper end of the side passage 15 guide theball plug during movement between the seated and unseated positions. Theramp 22 is formed by the transition between an enlarged diameter portion24 in the valve body 11 and the passage 14 which has a diameter equal tothe diameter of the well bore 13 and smaller than the diameter of theplug 16 thereby preventing the ball plug 16 from falling into thepassage 14.

A fluid pressure responsive operator, generally designated 26, is housedsubstantially outside the valve body 11 in a pair of concentric sleeves27 and 27a which are parallel to and offset from the bore 14. The upperend of sleeve 27a is threadably connected at 28 to the valve body 11 atthe lower end of the side pocket 15. The lower end of sleeve 27a isthreadably connected at 28a to the upper end of sleeve 27. The operator26 is adapted to move upward in the side passage 15 and parallel to themain passage 14. The inner bore of the sleeve 27a is provided with agroove 29 to receive a seal member 30. A second groove 31 is formed atthe lower end of the sleeve 27a within the sleeve 27 and receives a sealmember 310. Matching shoulders 32 and 33 on the operator 26 are adaptedto engage the seal members 30 and 31a, respectively, when the operator26 has moved to its uppermost position to provide secondary sealingbetween the operator 26 and the sleeves 27 and 27a. The operator 26includes a hollow cylindrical piston member 34 concentrically mounted inthe sleeves 27 and 2711, a telescoping member 34a positioned for limitedaxial movement within the upper end portion of the piston member 34 anda rounded nose portion 35 which extends beyond the sleeve 27 into theside passage 15. The nose portion 35 is threadably connected at 36 tothe upper end of the telescoping member 34a. An annular groove 38 on theupper inner surface of the sleeve 27a receives an O-ring 39 to seal theupper portion of the piston member 34 to the sleeve 27a. The lowerportion 40 of the piston member 34 is increased in diameter at 33 andthe outer surface of the lower portion 40 slidably contacts the lowerinner surface of the sleeve 27. The lower portion 40 of the pistonmember 34 has an annular groove 42 for receiving an O-ring 43 to sealthe lower portion of the piston member 34 to the sleeve 27.

The shoulder 33 on the piston member 34 also provides a piston surfacefor exposure to a control fluid pressure which is communicated from thewell surface by an auxiliary line 45. The control fluid pressure passesfrom the line 45 through a side inlet 47 in the sleeve 27a into anannular passage 46 between the upper portion of the piston member 34 andthe lower inner surface of the sleeve 27a into a second annular passage44 between the piston member 34 and the inner surface of the sleeve 27.The control pressure acts on the piston surface or shoulder 33 to effectdownward movement of the operator 26. Production or well tubing pressureacts up on the surface area of the operator defined by the O-ring 43 andacts down on the surface area of the operator defined by the O-ring 39.The area of the piston surface defined by O-ring 43 is greater than thearea of the piston surface within O-ring 39 and therefore the productionfluid pressure acts to cause an upward movement of the operator 26. Acap member 50 is interconnected by threads 51 to the lower end of thesleeve 27. The sleeves 27 and 27a and the cap member 50 define a pistonchamber. The cap member 50 includes a central opening 52 whichcommunicates the production fluid pressure from a conduit 53 to thepiston surface defined by O-ring 43. A side outlet 54 in the valve body11 communicates production fluid pressure from the bore 14 to theconduit 53.

A flange member 55 located below the side outlet 54 extends radiallyoutward from the valve body 11 to protect the conduit 53 when the welltubing is inserted into the well.

A spring 55a mounted axially within the hollow piston member 34 andbetween the lower end of the telescoping member 34a and the cap member50 also acts on the piston surface 48 to assist in the upward movementof the operator 26.

The downward movement of the operator 26 is limited by the cap member 50and the lower end of the sleeve 27 and the upward movement of theoperator is limited by the lower end of sleeve 27a.

Intermediate members 56 and 56a, each in the form of a ball, are locatedbetween the underside of the ball 16 and the nose portion 35 of theoperator 26. The present embodiment discloses the use of twointermediate members; however, it should be readily understood that oneintermediate member could be used without detracting from the scope ofthe invention. The intermediate members 56 and 56a are also carried bythe valve body 11 for bodily movement between a down position in theside pocket 15 and an up position in which intermediate member 56extends partially within the bore 14 and intermediate member 56a remainsoutside the bore 14. The inclined ramp 22 and the guide surface 23 guidethe intermediate member 56 during movement into the bore 14. Thediameter of the intermediate member 56 like the ball plug 16 is alsolarger than the diameter of the bore 14 and therefore cannot fall intothe bore 14.

The operation of the valve device is as follows:

At normal production fluid pressures, the ball plug 16 and theintermediate members 56 and 56a remain positioned in the side pocket 15offset from the bore or main passage 14 to allow fluid in the welltubing 12 to flow freely without restriction through the main passage orbore 14 in the valve body 11. This is accomplished by a pressure boostersystem (not shown) located at the well surface which maintains thecontrol line pressure at a higher pressure than the production linepressure. The ratio of production line pressure to control line pressuremight range from 1:154; to 1:2 depending on the customers needs. Thepressure that the booster operates on is taken directly from theflowline at the surface so that on a lzl /ratio booster, if the flowlinehas a 1,000 psi. flow pressure, the boosted pressure to the valve tohold it open would be 1,500 psi. The booster system also includes underand overpressure pilot valves (not shown). The underpressure pilot valveis designed to vent the pressure control line whenever the productionfluid pressure drops below a predetermined level and the overpressurepilot valve vents the control line whenever the production fluidpressure increases over a predetermined level. The operator 26 is heldin a down position with the lower end of piston member 34 against theupper end of the cap 50 by the combination of the control fluid pressureacting downward on the piston surface 33, and the production fluidpressure in passage 15 acting downward on the surface area of theoperator within the O-ring 39. When the well tubing or production fluidpressure increases or decreases beyond a predetermined level, thecontrol line pressure is decreased as a result of the pressure pilotvalves until the upward forces caused by the well tubing fluid pressureacting upward on the surface area of the operator defined by the O-ring43 and the force of the spring 55a exceed the downward forces acting onthe operator, at which time the operator 26 is moved upward and parallelto the main passage 14. The upward movement of the operator 26 causes asimilar upward movement of the intermediate members 56 and 56a and theball plug 16 with the intermediate members 56 and 56a transmitting theupward force of the operator 26 to the ball plug 16. Continued upwardmovement of the operator 26 forces the ball plug against the guidesurface 23 which guides the plug 16 into the bore 14 and onto the valveseat 17. The intermediate member 56 is similarly moved against the guidesurface 23 and continues to move upward along the guide surface 23 andinto the bore l4 until it is stopped by the seated ball plug 16. Theintermediate member 56 remains between and in contact with theintermediate member 560 and the ball plug 16, and the intermediatemember 56a remains between and in contact with the operator 26 and theintermediate member 56 to transmit the upward parallel force exerted bythe operator 26 to the ball plug 16 to move the ball plug upward into aseated position. Once the ball plug 16 is seated, the only force appliedto the plug 16 other than that caused by the production line pressure isthe force of the spring 550 transmitted by the telescoping member 344through the intermediate members 56 and 56a. Thisspring force acts tomaintain the ball plug 16 in the seated position. The seating of theball plug 16 prevents the flow of well fluid through the bore 14 of thevalve body 11 and into the well tubing 12. Thereafter, the valve may bereopened by pressuring down the well tubing 12 to overcome the upwardforces applied to the ball and at the same time increasing the controlfluid pressure to overcome the upward forces acting on the operator 26until the operator 26 moves downward and the intermediate members 56 and56a and ball plug 16 move downward and out of the flow stream into theside pocket 15.

It should be recognized that a parallel bypass well tubing 57 as shownby the broken lines in FIGS. 2 and 3 can be located in the well casingto allow well fluid to flow when the valve tubing 12 has been closed bythe valve device 10. Also, a valve assembly similar to valve assembly 10responding to the same or a different range of production fluidpressures can be connected into the well tubing 57.

This subsurface valve device operated from the well surface acts tocontrol the flow of fluid in the well tubing. When the control linepressure is maintained within a predetermined range, the valve plug andoperator are completely maintained outside the tubing bore therebyallowing a full bore opening to avoid restriction of well fluid flow andprovide an uninterrupted straight line path of communication verticallythrough the valve assembly. The valve includes 'a minimum number ofmoving parts and is simple in both operation and construction.

In the modified form of the invention shown in FIGS. 4, 5 and 6,provision is made for installation of a blocking sleeve 60 to hold theball plug 16 in the offset position and positively prevent it frommoving upward to contact the valve seat 17. The valve body 11a isprovided with an axial bore 61 below the valve seat 17 and extending toa taper shoulder 62. A tubular shoe 63 is originally installed to reston the shoulder 62 and is held in place by means of a shear pin 64. Theblocking sleeve 60 is also originally positioned within the bore 61 andthe lower end of this blocking sleeve 60 is received within the interiorof the shoe 63. An expanding split ring 65 is carried in a groove 66near the lower end of the blocking sleeve 60. The purpose of this splitring 65 is described below.

When the blocking sleeve 60 is in the original position shown in FIG. 4,the upper angular surface 67 thereof is positioned at a sufficiently lowelevation so as not to interfere with movement of the ball plug 16 fromits retracted of set position to its position engaging the seat 17. Theshear pin 63 on the valve body 11a projects into a recess 69 on theblocking sleeve 60 to hold it in position. Production fluid flows upwardthrough the interior of the blocking sleeve 60. The device of themodification of FIGS. 4, 5 and 6 then operates in the same manner asdescribed above in connection with the form of the invention shown inFIGS. 1-3. When the blocking sleeve 60 is in the position shown in FIG.4, and before the tool assembly 71 is lowered into position, theinclined surface 67 guides the ball plug 16 from the inoperative offsetposition to the position concentric with the seat 17.

if for any reason it should be desired to lock the ball plug 16 in itsoffset inoperative position and to positively prevent movement intosealing position on the seat 17, the blocking sleeve 60 is lifted fromthe position shown in FIG. 4 to the position shown in FIG. 5. Thislifting action is accomplished by means of a tool assembly generallydesignated 71 lowered through the tubing on a wire line, not shown, orhydraulically forced down through the tubing. This opening tool includesa mandrel 72 slidably mounted within a shell 73 and connected to theshell by means of shear pins 74. A transverse slot 75 slidably receivesa pair of oppositely directed dogs 76 and 77 each urged outward by meansof springs 78, 79, respectively. A cross pin 81 is carried by the shell73 and extends through he mandrel 72 and through triangular apertures 82provided in the lugs 76 and 77.

When the tool assembly 71 is lowered through the tubing and into thevalve body 11a, it enters the inten'or of the blocking sleeve 60, theouter ends of thedogs 76 and 77 dragging along the interior bore 83 ofthe blocking sleeve 60. Downward movement of the tool assembly 71 isarrested by contact of the shoulder 84. The dogs 76 and 77 move outwardunder force of th springs 78 and 79 to enter the internal grooves 85 and8 6' in the blocking sleeve 60. The parts are then in the position shownin FIG. 4.

in order to raise the blocking sleeve 60 to the position shown in FIG.5, the tool assembly 71 is lifted upward, to bring the shoulders 87 onthe dogs into engagement with the downward facing shoulder 88. Continuedupward movement of the tool assembly 71 breaks the shear pins 68 andbrings the extreme upper end 89 into contact with the lowermost portionof the seat 17. Continued upward movement of the tool assembly 71 breaksthe shear pins 74, lifting the mandrel 72 with respect to the shell 73and causing the cross pin 81 to retract the dogs 76 and 77 against theaction of the springs 78 and 79. As thus retracted, the dogs passthrough the interior bore 83 of the blocking sleeve 60 and the toolassembly 71 is withdrawn upwardly to the surface. The split expandingring 65 expands outward to contact the bore 61 in the valve body 110,thereby overlying the upper end 90 of the shoe 63, thereby holding theblocking sleeve 60 in its uppermost position. in this position, as shownin FIG. 5, the ball plug 16 contacts a relatively narrow slot 91 formedin the upper portion of the blocking sleeve 60 and this slot 91 is toonarrow to allow movement of the ball plug 16 radially inwardly. Flow ofproduction fluid then takes place through the interior of the blockingsleeve 60 and there is no possibility of the ball plug 16 moving intocontact with the seat 17. Rotation of the blocking sleeve 60 withrespect to the valve body 11a is prevented by engagement of the key 32within the keyway 93.

in other respects, the modified apparatus shown in FIGS. 4- 6 is thesame as that previously described in connection with F 165. 13.

lclaim:

1. A valve to control the flow of fluid in the bore of a well tubing,comprising: a valve body connectable in the well tubing string; saidvalve body having a main passage in alignment with the bore of the welltubing and a side passage offset from said main passage; a valve seatconcentric with said main passage; said valve body housing a plug and atleast one intermediate member; said plug adapted to move between saidside passage and a' seated position concentric with said main passage;said valve body having guide means to guide said plug during movement ofsaid plug; said guide means including a ramp proximate said side passageto guide said plug during movement into said side passage, said rampbeing downwardly and laterally inclined with respect to said mainpassage; said intermediate member being adapted to move in said sidepassage; pressure responsive operator means offset from said mainpassage and adapted to move into said side passage to effect movement ofsaid plug and said intermediate member; and said intermediate memberbeing maintained in operable contact and between said plug and saidoperator means to transmit the force exerted by said operator means tosaid plug when said plug is moved to the seated position.

2. A valve to control the flow of fluid in the bore of a well tubing,comprising: a valve body connectable in the well tubing string; saidvalve body having a main passage in alignment with the bore of the welltubing and a side passage offset from said main passage; a valve seatconcentric with said main passage; said valve body housing a plug and atleast one intermediate member; said plug adapted to move between saidside passage and a seated position concentric with said main passage;said valve body having guide means to guide said plug during movement ofsaid plug; said guide means including a guide surface at the upper sideof said passage to guide said plug during movement from said sidepassage, said guide surface being upwardly and laterally inclinedwithrespect to said main passage; said intermediate member being adapted tomove in said side passage; pressure responsive operator means offsetfrom said main passage and adapted to move into said side passage toeffect movement of said plug and said intermediate members; and saidintermediate member being maintained in operable contact between saidplug and said operator means to transmit the force exerted by saidoperator means to said plug when said plug is moved to the seatedposition.

3. A valve to control the flow of fluid in the bore of a well tubing,comprising: a valve body connectable in the well tubing string; saidvalve body having a main passage in alignment with the bore of the welltubing and a side passage offset from said main passage; a valve seatconcentric with said main passage; said valve body housing a plug and atleast one intermediate member, said intermediate member being in theform of a ball; said plug adapted to move between said side passage anda seated position concentric with said main passage; said intermediatemember being adapted to move in said side passage; pressure responsiveoperator means offset from said main passage and adapted to move intosaid side passage to effect movement of said plug and said intermediatemember; and said intermediate member maintained in operable contact andbetween said plug and said operator means to transmit the force exertedby said operator means to said plug when said plug is moved to theseated position.

4. The device of claim 3 wherein said valve body is provided with guidemeans to guide said plug during movement of said lug. p 5. The device ofclaim 3 wherein said operator means includes first piston surfaceslocated for exposure to control fluid pressure to effect movement ofsaid operator means in one direction and second piston surfaces locatedfor exposure to production fluid pressure to effectmovement of saidoperator means in the opposite direction.

6 The device of claim 5 wherein means are provided defining a pistonchamber, said first and second piston surfaces are maintained withinsaid piston chamber, and said operator means moves axially within saidpiston chamber.

7. The device of claim 6 wherein said piston chamber is in parallelalignment with said side passage and said means defining said pistonchamber are connected to said valve body.

8. The device of claim 5 wherein means are provided to communicatecontrol fluid pressure from the well surface to said first pistonsurfaces.

9. The device of claim 5 wherein means are provided to communicateproduction fluid pressure from the well tubing to said second pistonsurfaces.

10. The device of claim 3 wherein said plug is in the form of a ballhaving a diameter greater than the diameter of the bore of the welltubing.

11. The device of claim 3 wherein two intermediate members are used andeach is in the form of a ball.

12. A valve to control the flow of fluid in the bore of a well tubing,comprising: a valve body connectable in the well tubing string; saidvalve body having a main passage in alignment with the bore of the welltubing and a side passage offset from said main passage; a valve seatconcentric with said main passage; said valve body housing a plug and atleast one intermediate member; said plug adapted to move between saidpassage and a seated position concentric with said main passage; saidintermediate member being adapted to move in said side passage; pressureresponsive operator means offset from said main passage and adapted tomove into said side passage to effect movement of said plug and saidintermediate member; said operator means including a piston member, atelescoping member positioned for axial movement within said pistonmember and a nose portion connected to said telescoping member, saidpiston member having first piston surfaces located for exposure to acontrol fluid pressure to effect movement of said operator means in onedirection and second piston surfaces located for exposure to productionfluid pressure to effect movement of said operator means in the oppositedirection and said nose portion extending into said side passage; andsaid intermediate member being maintained in operable contact andbetween said plug and said operator means to transmit the force exertedby said operator means to said plug when said plug is moved to theseated position.

13. The device of claim 12 wherein means connected to said valve bodyare provided defining a piston chamber outside said valve body, saidpiston chamber is in parallel alignment with said side passage andoffset from the well tubing bore, and said first and second pistonsurfaces are contained within said piston chamber.

14. The device of claim 13 wherein spring means are provided within saidmeans defining said piston chamber to assist in the movement of saidoperator means into said side passage.

15. The device of claim 14 wherein said spring means act on saidtelescoping member to transmit a spring force on said plug when saidplug is in a seated position.

16. The device of claim 12 wherein first means are provided tocommunicate control fluid pressure from the well surface to L. saidpiston chamber and second means are provided to communicate productionfluid pressure from the well tubing bore to said piston chamber.

17. A subsurface valve to control the flow of fluid in the bore of awell tubing, comprising: a valve body connectable in the well tubing stg; aid valve body having a main passage in alignment with the bore ofthe well tubing, a downward facing valve seat concentric with said mainpassage, a side passage offset from said main passage, and a rampjoining said main passage and said side passage; a first ball moveablefrom said side passage on said ramp to close on said valve seat; and asecond ball positioned below said first ball and in contact therewithmoveable from said side passage onto said ramp while maintaining contactwith said first ball; and means for moving said first and second balls.

18. A valve to control the flow of fluid in the bore of a well tubing,comprising: a valve body connectable in the well tubing string andhaving a main passage in alignment with the bore of the well tubing anda side passage offset from said main passage, a downward facing seat inthe valve body in alignment with the main passage and positioned abovethe upper end of the side passage, a plug moveable from a positionwithin the side passage to a position to engage the seat to preventupward flow of fluid, pressure responsive means offset from said mainpassage for effecting such movement of said plug, and selectivelyoperable means for preventing movement of said plug into contact withsaid seat, said means including a blocking element movably mounted insaid main passage and moveable upward from an inoperative position to anoperative position, said blocking element in operative position having aportion blocking the path of movement of said plug to prevent it frommoving into engagement with said seat.

19. The device of claim 18 in which the plug comprises a ball.

20. The device of claim 18 in which the blocking element comprises asleeve having an inclined ramp at its upper end for guiding the plugtoward the seat.

21. The device of claim 20 in which means are provided for preventingrotation of the blocking sleeve within the valve body.

1. A valve to control the flow of fluid in the bore of a well tubing,comprising: a valve body connectable in the well tubing string; saidvalve body having a main passage in alignment with the bore of the welltubing and a side passage offset from said main passage; a valve seatconcentric with said main passage; said valve body housing a plug and atleast one intermediate member; said plug adapted to move between saidside passage and a seated position concentric with said main passage;said valve body having guide means to guide said plug during movement ofsaid plug; said guide means including a ramp proximate said side passageto guide said plug during movement into said side passage, said rampbeing downwardly and laterally inclined with respect to said mainpassage; said intermediate member being adapted to move in said sidepassage; pressure responsive operator means offset from said mainpassage and adapted to move into said side passage to effect movement ofsaid plug and said intermediate member; and said intermediate memberbeing maintained in operable contact and between said plug and saidoperator means to transmit the force exerted by said operator means tosaid plug when said plug is moved to the seated position.
 2. A valve tocontrol the flow of fluid in the bore of a well tubing, comprising: avalve body connectable in the well tubing string; said valve body havinga main passage in alignment with the bore of the well tubing and a sidepassage offset from said main passage; a valve seat concentric with saidmain passage; said valve body housing a plug and at least oneintermediate member; said plug adapted to move between said side passageand a seated position concentric with said main passage; said valve bodyhaving guide means to guide said plug during movement of said plug; saidguide means including a guide surface at the upper side of said passageto guide said plug during movement from said side passage, said guidesurface being upwardly and laterally inclined with respect to said mainpassage; said intermediate member being adapted to move in said sidepassage; pressure responsive operator means offset from said mainpassage and adapted to move into said side passage to effect movement ofsaid plug and said intermediate members; and said intermediate memberbeing maiNtained in operable contact between said plug and said operatormeans to transmit the force exerted by said operator means to said plugwhen said plug is moved to the seated position.
 3. A valve to controlthe flow of fluid in the bore of a well tubing, comprising: a valve bodyconnectable in the well tubing string; said valve body having a mainpassage in alignment with the bore of the well tubing and a side passageoffset from said main passage; a valve seat concentric with said mainpassage; said valve body housing a plug and at least one intermediatemember, said intermediate member being in the form of a ball; said plugadapted to move between said side passage and a seated positionconcentric with said main passage; said intermediate member beingadapted to move in said side passage; pressure responsive operator meansoffset from said main passage and adapted to move into said side passageto effect movement of said plug and said intermediate member; and saidintermediate member maintained in operable contact and between said plugand said operator means to transmit the force exerted by said operatormeans to said plug when said plug is moved to the seated position. 4.The device of claim 3 wherein said valve body is provided with guidemeans to guide said plug during movement of said plug.
 5. The device ofclaim 3 wherein said operator means includes first piston surfaceslocated for exposure to control fluid pressure to effect movement ofsaid operator means in one direction and second piston surfaces locatedfor exposure to production fluid pressure to effect movement of saidoperator means in the opposite direction.
 6. The device of claim 5wherein means are provided defining a piston chamber, said first andsecond piston surfaces are maintained within said piston chamber, andsaid operator means moves axially within said piston chamber.
 7. Thedevice of claim 6 wherein said piston chamber is in parallel alignmentwith said side passage and said means defining said piston chamber areconnected to said valve body.
 8. The device of claim 5 wherein means areprovided to communicate control fluid pressure from the well surface tosaid first piston surfaces.
 9. The device of claim 5 wherein means areprovided to communicate production fluid pressure from the well tubingto said second piston surfaces.
 10. The device of claim 3 wherein saidplug is in the form of a ball having a diameter greater than thediameter of the bore of the well tubing.
 11. The device of claim 3wherein two intermediate members are used and each is in the form of aball.
 12. A valve to control the flow of fluid in the bore of a welltubing, comprising: a valve body connectable in the well tubing string;said valve body having a main passage in alignment with the bore of thewell tubing and a side passage offset from said main passage; a valveseat concentric with said main passage; said valve body housing a plugand at least one intermediate member; said plug adapted to move betweensaid passage and a seated position concentric with said main passage;said intermediate member being adapted to move in said side passage;pressure responsive operator means offset from said main passage andadapted to move into said side passage to effect movement of said plugand said intermediate member; said operator means including a pistonmember, a telescoping member positioned for axial movement within saidpiston member and a nose portion connected to said telescoping member,said piston member having first piston surfaces located for exposure toa control fluid pressure to effect movement of said operator means inone direction and second piston surfaces located for exposure toproduction fluid pressure to effect movement of said operator means inthe opposite direction and said nose portion extending into said sidepassage; and said intermediate member being maintained in operablecontact and between said plug and said operator means to transmit theforce exerted by said operator means to said plug when said plug ismoved to the seated position.
 13. The device of claim 12 wherein meansconnected to said valve body are provided defining a piston chamberoutside said valve body, said piston chamber is in parallel alignmentwith said side passage and offset from the well tubing bore, and saidfirst and second piston surfaces are contained within said pistonchamber.
 14. The device of claim 13 wherein spring means are providedwithin said means defining said piston chamber to assist in the movementof said operator means into said side passage.
 15. The device of claim14 wherein said spring means act on said telescoping member to transmita spring force on said plug when said plug is in a seated position. 16.The device of claim 12 wherein first means are provided to communicatecontrol fluid pressure from the well surface to said piston chamber andsecond means are provided to communicate production fluid pressure fromthe well tubing bore to said piston chamber.
 17. A subsurface valve tocontrol the flow of fluid in the bore of a well tubing, comprising: avalve body connectable in the well tubing string; said valve body havinga main passage in alignment with the bore of the well tubing, a downwardfacing valve seat concentric with said main passage, a side passageoffset from said main passage, and a ramp joining said main passage andsaid side passage; a first ball moveable from said side passage on saidramp to close on said valve seat; and a second ball positioned belowsaid first ball and in contact therewith moveable from said side passageonto said ramp while maintaining contact with said first ball; and meansfor moving said first and second balls.
 18. A valve to control the flowof fluid in the bore of a well tubing, comprising: a valve bodyconnectable in the well tubing string and having a main passage inalignment with the bore of the well tubing and a side passage offsetfrom said main passage, a downward facing seat in the valve body inalignment with the main passage and positioned above the upper end ofthe side passage, a plug moveable from a position within the sidepassage to a position to engage the seat to prevent upward flow offluid, pressure responsive means offset from said main passage foreffecting such movement of said plug, and selectively operable means forpreventing movement of said plug into contact with said seat, said meansincluding a blocking element movably mounted in said main passage andmoveable upward from an inoperative position to an operative position,said blocking element in operative position having a portion blockingthe path of movement of said plug to prevent it from moving intoengagement with said seat.
 19. The device of claim 18 in which the plugcomprises a ball.
 20. The device of claim 18 in which the blockingelement comprises a sleeve having an inclined ramp at its upper end forguiding the plug toward the seat.
 21. The device of claim 20 in whichmeans are provided for preventing rotation of the blocking sleeve withinthe valve body.